1. Field of the Invention
The present invention is related to an apparatus for pumping viscous liquids. More particularly, the present invention is directed to an apparatus for pumping a tire sealant from a supply source into a tire.
2. Description of Related Art Including Information Disclosed Under 37 C.F.R. Sections 1.97-1.99.
A significant industry has been developed to install a viscous tire sealant material into pneumatic vehicle tires. Tire sealant permanently and automatically seals leaks up to about 0.6 cm, thereby saving time and money. Tire sealant can either be pumped into a mounted tire through the valve stem or pumped directly into the tire through the space between the tire bead and the wheel bead seat when the tire is mounted on a wheel, but not yet inflated.
Currently, two types of pumps are used to move the tire sealant from a supply source, typically a 200 liter barrel or 25 liter bucket, into the tire. A small hand operated pump has an external diameter of about 3-4 cm and a length of about 25-35 cm. A single piston is manually pulled upwardly while the lower end of the pump or an attached hose is immersed in a supply of tire sealant, drawing sealant into the pump's piston cylinder. Pushing down on the pump handle opens a ball valve in the hollow piston connecting rod, and the sealant material is forced upwardly through the hollow piston connecting rod into a line to the tire. This hand pump is suitable for small numbers of small jobs. Because the tire sealant is quite viscous, considerable exertion is required to force the material through the pump and tubes and use of this pump can be fatiguing. Further, it is not suitable for use with large tires, which can require up to 40-50 liters of tire sealant each and which can take ten minutes of hard hand pumping to fill with this pump because it has a capacity of only about 250 cc. Finally, using this pump uses far more time for pumping the material because it has a relatively small capacity, so it is not useful in high volume use.
Another pump used for installing tire sealant is a single piston pneumatic pump having a short stroke and a small chamber, which can pump only about 125 cc per stroke. This pump, called a stub pump, exerts very high air pressure with its small piston and short stroke. The volume of pumped sealant is determined by counting and regulating the number of stroke cycles. In addition, it is relatively expensive.
Therefore, there is a need for a pump for moving viscous materials that operates with readily available source of compressed air that can be preset and deliver an accurately determined volume of pumped material in a consistent manner; that is convenient and easy to use; that can be used with any size of pumped material container; that is easy to maintain and service; that can be adapted for use in various shop or field environments; and that is relatively inexpensive to manufacture.